Milo g



(No Model.)

M. G. KELLOGG.

MULTIPLE SWITGHBOARD.

No. 592,377. Patented Oct. 26,1897.-

4 illil Nrrn. STATES PATENT Fries.

MILO G. KELLOGG, OF CHICAGO, ILLINOIS, ASSIGNOR TO THE KELLOGG SIVITCI'IBOARD AND SUPPLY COMPANY, OF SAME PLACE.

M ULTIPLE SWITCH BOARD.

SPECIFICATION forming part of Letters Patent No. 592,377, dated October 26, 1897.

Application filed July 26, 1890. $eria1No. 360,088. (No model.)

To aZZ whom it may concern:

Be it known that I, MILo G. KELLOGG, of Chicago, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Multiple Switchboards for Telephone-Exchanges, of which the following is a full, clear, concise, and exact description, reference being had to the accompanying drawings, forming a part of this specification.

My invention relates to a metallic-circuit telephone-exchange system in which there is a cord and a plug attached to the cord for each line to which the line is connected. Said plug is inserted into the switch of another line when it is desired to switch the two lines together for conversation. Said system is called a single'cord system. I The plug generally rests normally (or when not in use for switching) in its own special switching device.

My invention consists in a system of testing, and in apparatus, circuit, and connections for each line, whereby the operator may expeditiously and with few movements connect her telephone to the circuit of the line when its call is indicated, may test the line wanted and at the same time ring the sub-.

scribers signal-bell when the line is not in use, may connect the two lines together, may connect her telephone to their circuit to determine whether they are through conversation, and may disconnect the lines and place the apparatus in readiness to receive a new call. Said system and apparatus are more simple and the work required is less than in other systems devised for a similar purpose.

In the accompanying.drawings, illustrating my invention, Figure 1 is a diagram illustratin g two switchboards and the main-line central-office apparatus of two lines, and Fig. 2

from the other parts except by the circuit connections. This contactpiece is adapted to have a plug applied to it for calling and testing. The switch shown in the drawings is of well-known construction.

For each line there is a compound answering switching device located at the board where the cordand plug of the line are located and where its calls are to be answered. This device is manipulated in part by the switch-plug when in the device and in part by the operator who answers the call. The construction, operation, and manipulation of these devices will hereinafter be explained in detail.

Two lines and their switches on the boards, their plugs and cords, their answeringswitches, and their annunciators are shown in the drawings. The answering apparatus of one line is shown as located at one board and that of the other line as located at the other board.

B B represent the two compound answering-switches, and D D the two switch-plugs of the lines, to which their double flexible conducting-cords are attached, and which are adapted to be placed in any spring-jack switch at the board Where they are located. One plug is shown in its switching device and one plug is shown out of its device ready to be inserted into the switch of any line.

In the compound answering-switches, a a are cylinders, preferably of metal, adapted to receive and guide the movable commutator and plug supporting pieces b. This piece may be of rubber, and is of the shape substantially as shown, and may be other shapes to correspond with variations which may be made in the construction, shape, and arrangement of the other parts.

1, 2, 3, 4, 5, and 6, are contact-pieces insulated from each other, as shown. 2, 4, and 5 are elastic pieces. The others may be rigid. The piece I) has a hole or socket in which the handle of the plug may be placed. It has also two chambers to receive the bent portions of springs 2 and 5, as shown, and has a shoulder which rests on the top of cylinder at when piece I) is moved to its lower position. In the chamber adapted to receive spring 5 is a shoulder or projection c, on which 5 presses when piece b is moved to its higher or outer position and which causes the contacts of the contact-pieces to change, as will be indicated.

Pieces 1 and 2 are mounted parallel to each other and in close juxtaposition, so that contact between them will be made and broken by the operation of the switch-plug, as will j be indicated. The pairs of contacts 3 4t and- 5 6 are mounted parallel to each other and in close juxtaposition, so that the contact of each pair is made and broken by the operation of the switch-plug, as will be indicated.

Spring 4 is connected near its upper end to 5 spring 5 by means of an insulating-piece fastened to both. It is therefore moved back and forth as spring 5 moves. Springs 2 and 5 are constructed and adjusted to press to- Ward the center of piece I), and will press against and be operated upon by the plug, as will be indicated. The pieces I) b are adapted to occupy two positions, the upper one shown a in B and the lower one in B. When theplug is in its socket in b, the piece I) occupies its lower position and the handle of the plug presses on 5 released from the pressure of the plug-handle and (the movable piece being still in its inner position) contact between 2 and 1 is broken and that between 5 and 6 and between 3 and i is established. When the plug is removed and the operator manipulates piece I) and 5 places it in its outer position, the contact between pieces 1 and 2 still remains broken and shoulder c, in the chamber of the piece, presses spring 5 out of contact with piece 6, and spring 4cis carried out of contact with piece 3. When, therefore, the plug is in the socket and thei; piece I) is in its lowerposition, 1 and 2 are in contact with each other and the other contacts of thedevice are out of contact. YVhen the plug is out'of the socket and piece I) is; still in its lower position, 1 and 2 are out of contact and 3 4t and 5 6 are in contact, respectively, and when the plug is out of the socket i and the piece I) is raised to its outer position, switch for use, while they are in the line-circuit while the telephone is on the switch or Theswitch-plugs D D are of a usual coni struction of loop-switch plugs adapted to be used with the spring-jack switches shown.; The outsides of the handles have a rubber in all three pairs are out of contact.

sulation. Each plug has two contact-pieces insulated from each other, one, s, at the end of the plug and the other, 8, along the plug- 1 cylinder tip. When a plug is inserted into any of the-switches,the piece 8 presses against frameor socket of the switch.

batteries, and r r resistance-coils.

connected to each other and to her answeringswitches, substantially as shown and as will be described.

w and x are calling-.annunciators, one for each line shown, and connected'into their respective circuits, as will hereinafter be described. They are preferably polarized annunciators.

G G are ground connections.

The connections are substantially as follows: One side or branch of each line passes normally successively through the pairs of contact-points of the line-switches, passing in each case to the spring first. It then passes through the line-annunciator and is then connected by one of the insulated conductors of the switch-cord to contact-piece s of the plug. It is also connected to contact-pieces 5 and 1 of the answering-switch of the line. The other branch of the line is connected to said third or insulated contact-pieces of its switches. It is also connected through the other conductor of the cord to contact-piece s of the plug, and is connected to contactpiece 3 of the answering-switch. Contactpiece 2 of this switch is connected to the ground. One side of the operators telephone is connected to contact-piece 40f the answering-switch and also to the groundthrough her calling-battery. The other side of the telewhile a battery of suitable strength is closed through its circuit. The contact points and connections are substantially as shown, but may be of other forms and arrangements which shall perform practically the operation required. They should be such that the sig nal-receiving bell or its contact-points are switched or shunted out of the circuit of the line while the subscribers telephone is off the not switched for use.

The operation of the system is as follows: When the plug of a line is in its normal position in the socket of its answering-switch and the line is not switched at any board, that branch of the line which passes through the several pairs of contact-points is grounded at the central office. WVhen the plug is withdrawn from its normal position, or a the spring of the switch and forces the spring 1 away from the contact-point and forms connection with the spring, and the other piece, s,'of-'t-he plug forms connection with the metal 3 plug is placed in one of its switches, this ground connection is removed. When the plug of a line is withdrawn from its normal position in the answering-switch, the two 1 sides or branches of the line are brought into 25 t are operators telephones, R R calling- 1 Each operator has'one of each of parts and they are j a closed circuit with the operators telephone in the circuit. The connection is automatically made by the closing of the two pairs of contact-points 3 4 and 5 6. The points 3 and 5 are connected to the two sides of the line and at and 6 are connected to the two sides of the telephone. The operator then by conversation finds out what line is wanted. She then places the tip 8 of the plug of the calling-line on the third or insulated contact-piece of the line wanted, and if the line is not switched at any board (and its normal ground connection broken) and the subscribers telephone is not switched for use a complete circuit is established, which contains the operators calling-battery and telephone and the subscribers circuit-breaking bell, and the bell will ring, calling the subscriber. This complete circuit is from the ground through the operators calling-battery and telephone-contacts 5 6 of the switching device of the plug used and the contact-piece s of the plug, thence through the circuit of the line and the subscribers bell when in the circuit, the normally closed contacts of the line-switches,and contacts 1 2 of the plug-switching device of the line to the ground. The operator also will distinguish in her telephone the make and break of a bell and will know that the line is free to be connected to. She will then push the plug into the switch and by so doing disconnect the line from its normal ground connection. The test-circuit (from the operators ground through her apparatus to the circuit of the line and through the line to its normal ground connection) will be broken and the bell will stop ringing. The two lines are thereby connected into a metallic circuit which is cross connected or bridged by a circuit which contains the operators telephone and resistance-coil, and the subscriber wanted has been called. The operator then raises the movable piece I) of the answering-switch and by so doing breaks the connections at 3 4. and 5 6 and removes the bridge connection. Should she wish at any time to listen into the circuit to determine whether the subscribers are through conversation, she will again establish the bridge connection by pressing in the piece 11 and a part of any telephone-current passing over the circuit will be deflected through her telephone. The use of the resistance-coil is to prevent an undue amount of the current from passing through the telephone. It will be observed that the subscribers bell will ring just so long as the operator holds the tip of the plug on his switch, and when the plug is pushed into the switch the bell stops ringing. It will also be seen that had the line been switched at any board by the use of its plug or through one of its switches, or had the subscribers telephone been switched for use and the bell thereby switched from the circuit, the bell would not have rung and the opera tor would not have got the signal which indicates that the line is clear. She would not, therefore, have switched the line with the line which desired the connection. A subscribers line, therefore, tests busy and is reserved to himself, whether it is switched at any board or his telephone is switched for use, and the service is more satisfactory than it would be were the test busy made by only one of these operations. Had the subscriber taken down his telephone for use when the test was made, but the line had not been switched at the central oflice, the operator would hear a single click in her telephone, but not a succession of sounds. She would then know that the subscribers telephone was switched for use, but that the line was not yet switched.

The operations to answer a call and complete a connection are these: First, to remove the plug from its normal position; second, to put the plug on the switch-contact of the line wanted and then push it into the switch, and, third, to raise or move up the piece Z) of the answering-switch. In order to listen to the circuit of two lines connected together, the operator merely pushes down on the piece 11 of the answering-switch and her telephone is connected in a bridge to their circuit.

The calling-batteries R B should be strong enough to operate the vibrating bell of any line when a battery and bell are closed to each other, as heretofore indicated. The number of cells required will depend on the resistance of the circuit (including line test receiving instrument, calling annunciator, and bell) and also on the character of the bell and the number of convolutions of its electromagnet. As a general thing as many as twenty-five or thirty, or even more, cells will be required for this purpose.

The operators telephone is used for the test receiving instrument. Other forms of test receiving instrument may be used,'but they should be such that when closed, as described, to the vibrating bell and the battery the instrument will respond to the vibrations of the bell.

The calling-annunciators should be connected into their respective circuits and the operators calling-batteries should be connected in the circuits in such a direction that the calling and testing current directed to any line will not operate the annunciator and give a false signal to its operator that the subscriber has sent in a call. The line-annunciators are distributed among the various boards of the exchange, and as the battery is a strong one an annunciator at a distant board might be made to indicate a call when a test is made were it not for this arrangement of the polarized annunciators and batteries; but by this construction and connection of the anuunciators and the batteries the false signals that the lines are wanted are prevented and confusion avoided. tVith electric batteries for signaling and testing and with ordinary polarized annunciators for receiving calls such connection is simple and easily understood by those skilled in the art.

The calling-generator shown in Fig. 2 has an automatic device with contact-points and connections by which the line-circuit is automatically grounded while the generator is operated with the generator in the line-circuit between such ground connection and the normal ground connection of the line at the central office. I use the terms bridge and cross-connect in connection with a complete metallic circuit to describe a connection between one side or branch of the circuit andits other side or branch, and an instrument in a bridge or cross-connecting circuit to a metallic circuit is not in the direct circuit, but is in a circuit connection across the two sides or branches of the circuit.

The subject-matter claimed herein is analogous to what is claimed in my application, Se-

- rial No. 360,089, except in this case (Serial No.

360,088) the claims recite a vibrating bell. The system of testing and calling is also shown in my application, Serial No. 361,114; but in the latter case the test and call battery is in the normal ground connection of the line at the central offlce.

Iclaim as myinvention and desire to secure by Letters Patent 1. In a telephone-exchange system, a metallic-circ uit telephone-line one side or branch of which is normally connected with the ground at the central office but disconnected from such ground While switched for conversation and the other side or branch of which is normally open at the central office, in combination with a vibrating bell at the subscribers station normally in the circuit of the line but switched or shunted from said circuit while the subscribers telephone is switched for use, and a test wire or circuit at the central office containing a test receiving instrument and battery, groundedat one end and connected at its other end to a plug or device adapted to be brought into connection with the normally open end of the line, said battery being so strong as to operate said bell and ground at the central oiiice but disconnected from such ground while switched'for conversation and the other side or branch of which is normally open at the central office,'in combination with a vibrating bell at the subscribers station normally in the circuit of such line but switched or shunted from such circuit while the subscribers telephone is switched for use, a test receiving instrument at the central office grounded on one side and connected on its other side to a test plug or device adapted to be brought'for testing into connection with the normally open end of the line, and a battery in the test-circuit established on testing, said battery being so strong as to operate said bell and said test receiving instrument being such as to respond to the make and break of the battery-current caused by the operation of said bell, substantially as set forth. V

3. In a telephone-exchange system, a metallic-circuit line, one side or branch of which is normally connected with the ground at the central office and the other side or branch of which is normally open at the central office, in combination with switching apparatus by which the line is disconnected from such ground connection while it is switched for conversation, a vibrating bell at the subscribers station, normally in the circuit of the line, a switch with contacts and connections by which the bell is shunted while the subscribers telephone is switched for use and a test wire or circuit at the central office, con taining a test receiving instrument and battery, grounded at one end and connected at its other end to a plug or device adapted to be brought into connection with such normally open end of the line, said battery being 1 so strong as to operate said bell and said test receiving instrument being such as to respond to the make and break of the battery-current caused by the operation of said bell, substantially as set forth.

4:. In a telephone-exchange system, a me- 1 tallic-circuit line one side or branch of which is normally connected with the ground at the central office and the other side or branch of which is normally open at the central office, in combination with switching apparatus by which the line is disconnected from such 5 ground connection while switched for conversation, a vibrating bell at the subscribers station, normally in the circuit of the line, a

switch with contacts and connections by which the bell is shunted while the subscribers telephone is switched for use, a test re- 3 ceiving instrument at the central office grounded on one side and connected on its other side to a test plug or device adapted to be brought into connection with the normally open end of the line, and a battery in the circuit established on testing, said battery being so strong as to operate saidbell and said test receiving instrument being such as to respond to the make and break of the battery-current 5 caused by the operation of said bell, substantially as set forth.

5. In a telephone-exchange system, a me- 5 tallic-circuit line, one side or branch of which 1 contains a polarized annunciator and is nor- 1 mally grounded at the central office but dis- 1 connected from the ground while switched for i conversation and the other side or branch of which is normally open at the central office,

'IIS

in combination with a vibrating bell at the subscribers station normally in the circuit of the line but switched or shunted while the subscribers telephone is switched for use,

and a test wire or circuit at the central office containing a test receiving instrument and battery, grounded at one end and connected at the other end to a plug or device adapted to be brought into connection with the normally open end of the line, the annunciator and battery being so connected into the circuit that the battery does not operate the an nunciator, said battery being so strong as to operate said bell and said test receiving instrument beingsuch as to respond to the make and break of the battery-current caused by the operation of said bell, substantially as set forth.

6. In a telephone-exchange system, a metallic-circuit line, one side or branch of which contains a polarized annunciator and is normally grounded at the central office and the other side or branch of which is normally open at the central oiiice, in combination with switch apparatus by which the line is disconnected from such ground connection while switched for conversation, a vibrating bell at the subscribers station, normally in the circuit of the line, a switch with contacts and connections by which the bell is switched or shunted from the line while the subscribers telephone is switched for use, a test receiving instrument grounded on one side and connected on its other side to a plug or device adapted to be brought into connection with said normally open end of the line, and'a battery in the circuit thereby established, the annunciator and battery being so connected into the circuit that the battery does not operate the annunciator, said bat-tery being so strong as to operate said bell and said test receiving instrument being such as to respond to the make and break of the battery-current caused by the operation of said bell, substantially as set forth.

7. In a telephone-exchange system, a metallic-circuit line, one side or branch of which contains an annunciator and is normally grounded at the central oflice but disconnected from the ground while switched for conversation and the other side or branch of which is normally open at the central office, in combination with a vibrating bell at the subscribers station, a switch with contacts and connections by which the bell is switched or shunted from the circuit while the subscribers telephone is switched for use, and a test wire or circuit at the central office, containing a test receiving instrument and battery, grounded at one end and connected at its other end to a test plug or device adapted to be brought into connection with the normall y open end of the line, said annunciator and battery being so constructed and connected that when thus connected in a circuit the battery does not operate the annunciator, said battery being so strong as to operate said bell and said test receiving instrument being such as to respond to the make and break of the battery-current caused by the operation of said bell, substantially as set forth.

8. In a telephone-exchange system, a me tallic-circuit line one side or branch of which contains an aununciator and is normally grounded at the central office and the other side or branch of which is normally open at the central office, in combination with switch apparatus by which the line is disconnected from such ground connection while switched for conversation, a vibrating bell at the subscribers station normally in the circuit of the line but switched or shunted from such circuit while the subscribers telephone is switched for conversation, a test receiving instrument at the central office grounded on one side and connected on its other side to a plug or device adapted to be brought into connection with the normally open end of the line,and a battery in the circuit thereby established, said annunciator and battery being so constructed and connected that when thus connected into a circuit the battery does not operate the annunciator, said battery being so strong as to operate said bell and said test receiving instrument being such as to respond to the make and break of the battery-current caused by the operation of said bell, substantially as set forth.

9. In a telephoneexchange system, a metallic-circuit line normally disconnected from the ground at the subscribers station, one side or branch of which is normally connected with the ground at the central office but disconnected from such ground connection while switched for conversation, in combination with a vibrating bell at the subscribers station, normally in the circuit of the line but switched or shunted from the circuit while the subscribers telephone is switched for use, and a test wire or circuit at the central oflice, containing a test receiving instrument and a battery, grounded on one side and connected on its other side to a plug or device adapted to be brought into connection with the normally open end of the line, said battery being so strong as to operate said bell and said test receiving instrument being such as to respond to the make and break of the battery-current caused by the operation of said bell, substantially as set forth.

10. In a telephone-exchange system, a metallic-circuit line normally disconnected from the ground at the subscribers station, one side or branch of which is normally connected with the ground at the central oflice and the other side or branch of which is normally open at the central oi'tice, in combination with switching apparatus by which such ground connection at the central office is broken while the line is switched for conversation, a vibrating bell at the subscribers station normally in the circuit of the line, a switch with contact-s and connections by which the bell is switched or shunted while the subscribers telephone is switched for use, a test receiving instrument at the central office grounded on one side and connected on its other side to a plug or device adapted to be brought into connect-ion with the normally open end of the line, and a battery in the circuit thereby established, said battery being so strong as to operate said bell and said test receiving'instrument being such as to respond to the make and break of the battery-current caused by the operation of said bell, substantially as set forth.

11. In a telephone-exchange system, a metallic-circuit line normally disconnected from the ground at the subscribers office, one side or branch of which contains a polarized annunciator and is normally grounded at the central office but disconnected from the ground While the line is switched for conversation and the other side or branch of which is normally open at the central office, in combination with a calling-generator at the subscribers station, contact-points and connections by which the line is grounded while the generator is operated with the generator in circuit between such ground connection and the normal ground at the central office, a vibrating bell normally in the circuit'of the line at the subscribers station but switched or shunted from circuit while the subscribers telephone is switched for use and a test wire or circuit containing a test receiving instrument and a battery, grounded at one end and connected at its other end to a plug or device adapted to be brought into connection with the normally open end of the line, said battery being so strong as to operate said bell and said test receiving instrument being such as to respond to the make and break of the battery-current caused by the operation of said bell, substantially as set forth.

12. In a telephone-exchange system, a metallic-circuit'line normally disconnected from the ground at the subscribers station, one side or branch of which contains a line-annunciator and is normally grounded at the central office and the other side or branch of which the line is grounded while the generator is operated with the generator between such .grou'nd connection and the normal ground connection of the line at the central office, a vibrating bell at the subscribers station normally in the circuit of the line, a switch with contacts and connectionsby which the bell is switched or shunted from the circuit while the subscribers telephone is switched for use, a test receiving instrument at the central office, grounded on one side and connected on its other side to a plug or device adapted to be brought into connection with the normally open end of the line, and a battery in the circuit thereby established, said battery being so strong as to operate said bell and said test receiving instrument being such as to respond to the make and break of the battery-current caused by the operation of said bell, substantially as set forth.

13, In a telephone-exchange system, a metallic-circuit line one side or branch of which is norm ally grounded at the central office and the other side or branch of which is normally open at the central office, in combination with switching apparatus .by which such normal ground connection is broken while the line is switched for conversation, a vibrating bell normally in the circuit of the line at the subscribers station, a switch with contact-points and connections by which the bell is switched or shunted from the circuit while the subscribers telephone is switched for conversation, connecting apparatus by which the op erator may temporarily ground such normally openside or branch of the line, and a'battery in the circuit which may thereby be established, said battery being so strong as to operate said bell, and the test receivinginstrument being such as to respond to the vibrations of the bell when they are thus included in closed circuit with each other, substantially as set forth.

14. In a telephone-exchange system, a metallic-circuit line which is normally disconnected from the ground at the subscribers station and has a vibrating bell there in its circuit while his telephone is not switched for use and only then, one side or branch of 9 the line being normally grounded at the central office and the other side or branch of the line being normally open at the central office, in combination with apparatus by which the operator may ground such normally open side or branch of the line and a battery in the circuit thereby established, said battery being so strong as to operate said bell when they are thus included in closed circuit with each other, substantially as set forth.

15. In a telephone-exchange system, a metallic-circuit line which is normally disconnected from the ground at the subscribers station and has there a vibrating bell in its circuit while his telephone is not switched for use, one side or branch of the line being normally grounded at the central office and the other side 'or branch being normally open at the central office, in combination with switch apparatus by which such normal ground connection is broken while the line is switched for conversation, connecting apparatus by which the operator may temporarily ground such normally open side or branch of the line, and a battery in the circuit thereby established, said battery being so strong as to operate said bell when they are thus included in closed circuit with each other, substan-' tially as set forth.

In witness whereof I hereunto subscribe my name this 23d day of June, 1890.

EMIL ABENHEIM, O. STRICH-CHAPELL.

too 

